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问题 选择题

下列应用或相应原理(用化学方程式表示)及基本反应类型都正确的是………(      )

A．在实验室制取氧气 2 KMnO4△K2MnO2+MnO2+O2↑分解反应

B．溶洞的形成CaCO3+ H2O + CO2= Ca(HCO3)2化合反应

C．用盐酸除水垢Mg(OH)2 +2HCl=" Mg" Cl 2+ H 2O复分解反应

D．高炉炼铁的主要反应2C + Fe3O4高温3Fe +2CO2↑置换反应

答案

答案：B

题目分析：A、实验室制取氧气：2 KMnO4△K2MnO4+MnO2+O2↑，属于分解反应，错误，B、正确，C、水垢的主要成分是碳酸钙，用盐酸除水垢发生的反应为：CaCO3+2HCl==CaCl2+H2O+CO2↑，D、高炉炼铁的主要反应，主要是利用一氧化碳的还原性，发生的反应为：3CO+ Fe2O3高温2Fe + 3CO2，故选B

填空题

Part 4


Questions 26-45


·Read the following passage and decide which answer best fits each space.
·For questions 26-45, mark one letter A, B, C or D on the Answer Sheet.
Participation (26) high school sports is not a constitutional right. (27) , it is a privilege, paid for by taxpayers, open to students who promise to (28) certain conduct requirements on and off the field. One of these promises is to (29) from using drugs. Drug use is a serious problem among high school students. Studies show that as many as 500, 000 high school students use muscle-pumping, life-destroying substances such as steroids. Many more use illegal drugs, (30) cause discipline problems and (31) the stage for lifelong (32) .
Drug testing works to (33) and identify use. That is why drug testing is required to compete in the Olympics, the National Collegiate Athletic Association and the National Football League. (34) drug testing was instituted by these organizations, use of performance- (35) drugs has been greatly reduced. We should want (36) in schools.
Indeed, many athletes (37) testing programs, and no wonder. Without testing, athletes have to choose between drug use and a competitive disadvantage (38) the field.
Those who challenge the need for drug testing may be forgetting (39) it is like be an adolescent. Peer pressure is enormous, and one of the few effective counter-weights is the fear of being caught. More importantly, once drug use is (40) , a school can (41) to the student before he or she gets addicted or arrested.
For 25 years, public schools (42) by federal judges and civil libertarians, with results everyone can see. It is time (43) decisions on how to run public schools locally (44) officials. There is nothing unconstitutional about asking those who gain the advantages of school-sponsored athletics to contribute to the safety of other players, the integrity of the game and their own well-being. The Supreme Court should leave these programs (45) .

A．But

B．Rather

C．Therefore

D．Thus
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问答题 简答题

影响反射波振幅的因素。
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